JPS5859225A - Cation exchange membrane - Google Patents

Abstract

PURPOSE:A cation exchange membrane having a high current efficiency and excellent durability, prepared by using a thermoconductive base coated with an insulating substance as a core material. CONSTITUTION:A core material is obtained by forming a metal or carbonaceous substance having a thermal conductivity >=0.001cal/sec. cm. deg.C, (e.g., Fe, carbon fiber) into a net-like material, thickness <=5mm. and opening <=5mm., and coating the net-like material with an insulating substance (e.g., polyvinylidene fluoride). Then, to both sides of the core are bonded, by fusion, a membrane-form cation exchange resin (e.g., tetrafluoroethylene/perfluoroalkyl vinyl ether sulfonylfluoride copolymer). The ion exchange membrane thus-produced does not cause mixing between anolyte and catholyte, and can be applied to electrolysis in a system in which selective permeation of cations is required, for example, an organic electrolytic reaction or electrolytic dimerization of acrylonitrile.

Description

[Detailed description of the invention] Aeon 5 using wood as the core material! :Provides replacement membranes.

Conventionally, several methods have already been proposed for ion-patric membrane salt electrolysis. For example, a two-chamber electrolysis method using a fluorine-based ion exchange layer and a three-chamber electrolysis method using a protective diaphragm in addition to an ion exchange membrane.

Various modifications have been proposed for each of them, which can be said to be their basic aspects. However, the common defect among them is low current efficiency or otherwise the durability of the film is affected. There is a gap.Originally 1a
[In cases where the fi efficiency is low (in some cases, it seems obvious, even if the film shows good performance at first, it gradually deteriorates in terms of performance such as electrical resistance and current efficiency, and physical properties such as mechanical strength). becomes recognized.

The cause of this kind of deterioration is force ζ current @
Since the deterioration progresses significantly when the temperature is increased, it is inferred that heat generation inside the membrane during energization is probably one of the major causes. That is, such heat generation, in conjunction with current distribution, non-uniformity of film composition, etc., causes a localized temperature rise inside the film, which causes the film to deteriorate.

The inventors of the present invention have taken into consideration the above points, and as a result of various studies,
It has been shown that the above problems can be solved by using a thermally conductive base material, that is, a thermally conductive material covered with an insulating material, as the core material, or packing, of the ion exchange membrane. I found it.

That is, the present invention is a cation exchange layer using a thermally conductive base material covered with an insulating material as a core material.

The base material used for the core material in the present invention is thermally conductive and is not particularly limited, but generally has a thermal conductivity of 0.00/c&I3/lee@cm.
C or more preferably 0 # 003 ca-#/see
Those with a temperature of @mΦ°C or higher are well used. Specifically, a metal or carbonaceous mesh material is particularly preferably used.

Hereinafter, a net-like material will be explained as a representative core material.

There are no particular limitations on the metal network as long as the constituent metals are not severely eroded under electrolytic conditions. For example, T1.2'', Nb% Ta, Mo, W.

F・, CosNlsCu, ＾g%Au
% Ru % Rh s Pd sCo, lr
, Pt%V%Cr, Mn, or alloys thereof can be suitably used. In addition, as a carbonaceous network material,
In addition to woven fabrics, mats, etc. made of various carbon fibers, materials such as graphite film can also be used.

There is no limit to the shape of these nets.Extremely thick nets are undesirable because they not only make the battery case unnecessarily large but also increase the electrical resistance of the membrane itself. In general, a thickness of S or less, preferably 0.03 wm or more with a thickness of S or less, is suitably used. There is also no restriction on the shape of the mesh, and in addition to those with the shape of plants being used, perforated plates, sponge-like ones, and indestructible cloth are also used, so there is no ant color. In other words, it is a general term for perforated plates that include perforated plates and sponge-like materials in addition to nets.

Furthermore, there is no particular restriction on the size of the mesh (void) as long as it does not interfere with the passage of ions, but if the mesh has extremely large openings, the effect will be weak, so is S
Those having a diameter or angle of 1 wm or less, preferably 1 wm or less are suitably used.

Furthermore, what is interesting is that the core material of the ion exchange membrane of the present invention has a charge that the ion exchange groups of the ion exchange membrane have and
A potential of the sign is obtained by applying a charge from the outside of the ion exchange membrane and performing electrolysis. That is, in the case of a cation exchange membrane, the ion exchange group generally has a negative charge, so
For example, a negative potential of the same sign as that of 141. The polymer used as a core material when manufacturing the cation exchange membrane of the present invention has thermal conductivity and gas conductivity, and has ion exchange properties or can be converted into ion exchange properties. When attaching the PFyA substance, it is necessary to interpose an insulating material between the base material which becomes the core and the molecular substance. For example, after coating the base material that will become the core material in advance with a substance that does not have electrical conductivity or ion conductivity, and then attaching a substance that has ion exchange properties or can easily impart ion exchange properties, the necessary An ion converting group may be introduced by.

The potential to be applied to this thermally conductive and electrically conductive core material is not particularly limited. That is, a potential of several lO'Ov from i and V may be applied. At this time, for example, the cation exchange membrane has a negative electrostatic potential, that is, the interface within the 111thl tag of the ion exchange membrane has a negative potential, selectively transmitting cations and blocking the permeation of other ions. function is facilitated.

By the way, the potential applied to the material of the ion exchange membrane in this way may be applied continuously at the negative potential, but it may also be applied intermittently. Alternatively, it may be a pulsating current wave obtained by rectifying a countercurrent (・. In this case, the frequency of the pulsating current is not particularly limited (・. may be overused.

Most of the core materials with thermal conductivity and electrical conductivity have excellent mechanical strength, so they are comparable in terms of reinforcing function as Pk steel core materials.

Furthermore, by maintaining the shape of the core material appropriately, it is also possible to produce membranes with intricate shapes. That is, the shape of the core material may be appropriately selected and the ion conversion resin may be laminated thereon.

For example, a mold that fits the required curved surface is made, a core material is sandwiched between the molds, and a JIjLii body mixture is poured into the mold for polymerization, or a thermoplastic resin is heated and pressurized together with the core material. Molding, etc., or making a flat plate,
An ion-exchange membrane with a similar shape can be produced by various methods, such as a method in which the membrane is formed and then transformed into an arbitrary shape.

The type of ion-exchange resin membrane used in the present invention is not particularly limited and can be selected depending on the situation. Also,
The method of manufacturing a membrane using a metal or carbonaceous mesh material as a core material is not limited in any way, and any method that can be conceived by a normal engineer may be adopted.

Some examples of methods for producing cation exchange membranes using a thermally conductive base material as a core material will be shown below.

2) In the case of a heterogeneous cation exchange membrane, a 1-condensation cation exchange resin or an inorganic ion exchanger may be used.
The powder is uniformly mixed with a suitable thermoplastic polymer, a mesh covered with an insulating material is embedded therein, and the mixture is heated and molded into a film. In addition, the above-mentioned fine powder ion exchange resin is uniformly dispersed in a viscous primer solution, which is commonly understood as a linear polymer, and this is coated on the network by coating, dipping, spraying, etc., and the solvent is scattered to form a film. Good too. Or inorganic ions '5!
The net-like material may be embedded in a mixture of cement and the like to form a membrane.

In this way, the network-containing ion exchange membrane can be produced by applying the conventionally known technology for producing unrestricted ion membranes.

(e) Like rW1, homogeneous cation exchange membranes were also coated with trout-like minerals using various techniques conventionally proposed for the production of homogeneous ion exchange membranes. Ion exchange membranes containing mesh can be made.

Next, some embodiments include (-) coating with an insulating material directly by means of coating @ dipping/spraying using a polymerizable functional monomer such as mass, vinyl, allyl, etc. There is an embodiment in which the net-like material is coated and the material is heated and polymerized. In this case, it is necessary to prevent the polymerization raw material liquid from dripping! If there is, the viscosity of the polymerization raw material may be adjusted depending on the shape of the net, or it may be covered with a suitable film such as cellophane. The liquid viscous coating solution used here uses one or more types of fluorine-containing vinyl and aryl monomers, and in order to increase the viscosity, it is appropriately coated with a soluble oxidation-resistant polymer finely dispersed powder. Oxidizing rich molecules may also be present.

This appropriately mixed viscous material is used to directly coat the net-like material by means such as dipping or spraying, and in addition to heating under f'Lk pressure or normal pressure, it is also sulfonated if necessary. Introduction of a cation exchange group or conversion into a cation exchange group may be carried out by hydrolysis or other known means.

If Togane is composed of an insoluble polymer structure, it may be polymerized either radically or ionically, and radiation, X-rays, light energy, etc. may be used.

(b> Next, there is a method using a linear polymer electrolyte. In other words, a fluorine-containing anionic polymer electrolyte is dissolved in a suitable solvent, and this is used to coat the net-like object covered with the coating material. After that, the solvent is scattered, and if the remaining film is insoluble, it is left as is, or if it is soluble, it is made insolubilized by appropriate means such as radiation irradiation, X-ray irradiation, or ultraviolet irradiation. can do.

These are just some examples.
It is also effective to heat a thermoplastic polymer electrolyte that is insoluble in acidic/basic aqueous solutions to coat the network and, if necessary, introduce ion exchange groups. As this type of linear polymer, one represented by Shaji CF2-CF25o2X is particularly effective. (However, m is a positive integer, t, n are 0 or positive integers, X is halogen or -OH
(c) There is also a method using an inert polymer compound. That is, polyvinyl fluoride, previnylidene fluoride, polytrifluoroethylene chloride, yj? A thermoplastic polymer of ethylene ethylene fluoride (IJ) is deposited on a net-like material covered with an insulating material by heat molding to form a thin film-like material.
An ion exchange group is introduced into this by some method. The method of attaching the polymer is not particularly limited, and examples include methods of dissolving or dispersing one or more of the above-mentioned polymer compounds in a suitable solvent, immersing the above-mentioned net-like material in the solvent, and scattering the solvent; A method of scattering the solvent by applying or spraying the solution/dispersion, or a method of electrostatically charging the fine powder of the above-mentioned polymer and also charging the net-like material with an opposite charge to form a fine powder. A method of electrostatically adhering a substance and heating it to fuse a finely powdered polymer to form a film-like material, and a method of melting the above polymer at a high temperature that does not cause thermal decomposition. A method in which the net-like material is immersed and attached, a method in which the polymer is molded using the net-like material as a core, etc. are effective. The most suitable method may be selected depending on the type of polymer compound used, the physical properties of the polymer such as molecular weight, the material and shape of the network, and the purpose of use of the network-containing ion exchange membrane.

The attached polymeric compound Kij ion exchange group must be introduced. As a method for introducing ion exchange groups, if the attached polymer is a polymer into which ion exchange groups can be introduced, it may be directly treated with an ion exchange group introduction reagent. In addition, the adhered polymer compound is impregnated with a polymerizable vinyl or aryl compound at room temperature or under heating, and at the same time, a radical polymerization initiator is coexisted, and the impregnated compound is impregnated under conditions such as under pressure that the impregnated compound does not scatter. What is necessary is to carry out heating polymerization. In this case, a crosslinkable monovinyl compound may be present to form a three-dimensional structure, or a linear structure may be formed. Moreover, the polymerization means is not limited to radical polymerization, but may be cationic polymerization, anionic polymerization, or redox polymerization. Furthermore, if the adhered polymer is impregnated with an excessively large amount of vinyl or aryl compound, resulting in significant dimensional changes and weak mechanical strength, add an appropriate solvent to the impregnated amount to dilute and impregnate. May be decreased. If the amount of impregnation is small, the pre-adhered polymer may be swollen with a solvent and then immersed in the monomer. Of course, the impregnated lid can also be increased by heating.

In addition to the above-mentioned impregnation method, a vinyl or polymer monomer may be graft-polymerized onto a polymer adhered by radiation or the like. In this case, the pre-adhered polymer may be irradiated with radiation to form radicals, and then immersed in the monomer or monomer mixture. Alternatively, it may be impregnated into RP-VC and then irradiated with radiation to polymerize. Among these various methods, the most suitable method may be adopted depending on the purpose of use of the ion exchange membrane containing the mesh, the type of polymer attached, the shape of the mesh, the material, etc. For example, a sheet of vinylidene fluoride is heat-fused onto a net-like material, and this is immersed in acrylic acid or a mixture of acrylic acid and styrene, divinylbenzene, etc.
A method in which fluorination is carried out after graft polymerization by irradiation with radiation, or a method in which tl'Q ethylene is heated to fuse it onto a net-like material, and this is heated to form a mixture of methacrylic acid, divinylbenzene, and hypenzoyl peroxide. Examples include a method of obtaining the cation exchange membrane of the present invention by immersing it in a mixed solution, sufficiently impregnating the adhered polyethylene, and then heating and polymerizing it in an autoclave under high pressure to form bales and fluorination treatment.

(d) There is also a mold polymerization method. That is, vinyl R is added to acrylic acid, methacrylic acid, styrene sulfonic esters, vinyl sulfonic esters, etc.
Add a cross-linking agent such as Zhenzene, further add a radical 1 initiator, and if necessary, add other additives such as a solvent as a diluent, a linear polymer, a fine powder cross-linkable polymer, etc. This is a method in which the net-like material is inserted as a core into a mold corresponding to the shape of the net-like material covered with an insulating material, and then the above-mentioned monomer mixed solution is poured and polymerized by heating. In this case, if there is no oxidation resistance, fluorination treatment may be performed to impart oxidation resistance.

Although some examples for making the ion exchange membrane of the present invention have been shown above, the present invention is not limited to the above examples in any way.

Furthermore, the present invention is characterized in that the polymer having a cation exchange group is in the form of a membrane, and contains an insulating, sword-like, and covered net-like substance inside it. crack,
The presence of pinholes is also not allowed.

That is, it is preferable that water permeation and filtration under pressure be as low as that of a normal ion exchange resin membrane. In other words, the water permeability is /
Q-5CC/dm2. It is desirable that it be less than or equal to matm*s@c.

When the ion-exchange membrane of the present invention is used for alkali metal salt electrolysis, anions are added to the generated alkali (1) to improve the efficiency of the current of the hydroxide. An exchangeable thin layer may be present, or a neutral thin layer may be present. Particularly preferred in this case is the case where the thin layer is crosslinked and densely distributed. Also,
When this anion exchange or neutral thin layer is physically or chemically attached or adsorbed, the cation exchange resin part and the thin layer are intertwined with polymer chains at the interface. The bond may be attached by an ionic bond, a covalent bond, a coordinate bond, or the like. The thin layer may then be present in a layered manner over the cation resin part, or may be present by a suitable chemical reaction towards the interior of the molded cation exchange resin part. In addition, the method of impregnating and polymerizing ion-exchange, neutral, and anion-exchange monomers, which we proposed earlier, is also effective.

In this case, fluorination may be performed afterwards. The above treatment provides advantages such as improving the current efficiency of the cation exchange membrane itself and improving the purity of the alkali metal hydroxide produced.However, if the post-treated material does not have brewing resistance, it may be necessary to fluorinate it. Alternatively, the oxidizing agent may be present inside the cathode-measuring film where no oxidizing agent is present.

Further, as the ion exchange group to be bonded to the cation exchange resin portion of the present invention, any conventionally known functional group that can be negatively charged in an aqueous solution can be used without any restriction. Namely, sulfonic acid group, carboxylic acid group, phosphoric acid group, phosphorous acid group, sulfuric acid ester group, phosphoric acid ester group, phosphorous acid ester group, phenol group, thiol group, oxalic acid group, silicate group, tin It's acidic. It is sufficient that these ion exchange groups are present to the extent that it functions as an ion exchange membrane.

Also, the surface layer is thin! The anion-exchangeable thin layer that is present in the - form has a functional group that becomes a solid charge in an aqueous solution; 1st Iv&, Phosphonium, Arsonium, Styt? = um, cobaltidinium, and other onium tM groups. It is effective both when there is no functional group that can dissociate in Fir<aqueous solution as a neutral thin layer, and when the above-mentioned anion exchange group and cation exchange group are present in approximately equal proportions. be.゛If a thin layer exists on the surface layer, an ion exchange resin component exists on top of this anion exchange thin layer and neutral thin layer, forming an anion exchange resin component like a sandwich. , a thin cation exchange layer may be present.

The embodiment using the ion exchange membrane of the present invention is not particularly limited, and can be used for electrolysis in a system where mixing of the anolyte and catholyte does not occur and selective permeation of cations is required. For example, it is effective for use in organic electrolytic reactions and electrolytic trimerization reactions of acrylonitrile.

In addition, it can be used not only for alkali metal salt electrolysis but also for a wide range of electrolysis reactions of inorganic electrolyte solutions.

It is particularly effective for the electrolysis of alkali metal salts, i.e., halides, sulfates, nitrates, phosphates, etc. of lithium, sodium, potassium, rubidium, cesium, etc. It is also effective for the electrolysis of acids, i.e., hydrochloric acid, sulfuric acid, nitric acid, A vine used for electrolysis of phosphoric acid, etc.

As the ion exchange resin part of the present invention, it is generally preferable to use a oxidation-resistant material such as a fluorine-based material. When the part is configured, it can be used by installing it between the +S pole and the cathode.
When the cation exchange resin part is composed of 1.7
In order to prevent oxidative deterioration of the resin part caused by oxidizing substances generated from the anode during the main electrolysis, the cation exchange membrane part is treated with acid resistance such as fluorination or chlorination, as described above. All you have to do is

Therefore, there is no restriction in any way.

EXAMPLE A membrane-like material was molded using a polymer having an exchange capacity of 0.9/msq/I obtained from a copolymer of tetrafluoroq ethylene and perfluoroalkyl vinyl ether sulfonyl fluoride PO.

That is, a nickel wire mesh made of lOO mesh was immersed in a solution of 4η vinylidene fluoride in dinchylformamide, pulled out and air-dried, and then heated in an air dryer at 180°C to dissolve the nickel. On the wire mesh? A thin film of vinylidene fluoride was formed for insulation. Next, a sulfonyl fluoride type book was fused to this core material from both sides using the above copolymer to form a diaphragm. This is A, 0NKOH
It was immersed in water to be hydrolyzed and converted into potassium sulfonate.

Using this membrane, electrolysis of saturated saline was carried out using a two-base method. That is, saturated saline was used as the anolyte, and A and ONNaOH were obtained from the cathode. The current efficiency of this ibis was 72chi. Next, the negative pole of a 2θOv DC power supply was connected to this diaphragm, and the positive pole of the DC power supply was connected to the cathode and electrolysis was carried out in the same manner, and the current efficiency was g6. The current density during electrolysis was 30^/dm2, and the liquid temperature was 7.5-'C. .

Patent applicant: Tokuyama Soda Co., Ltd.

Claims (1)

[Claims] 111 A cation exchange layer using a thermally conductive base material made of an insulating material as a core material.